Angle variable mechanism and desktop apparatus

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-331142, filed on Dec. 21, 2007, the entire contents of which are incorporated herein by reference.

1. Field

One embodiment of the invention relates to an angle variable mechanism varying a swing angle of a movable unit with respect to a fixed unit. In addition, the embodiment relates to a desktop apparatus such as a telephone in which an apparatus body having a handset and a display portion is swingably attached to a base placed on a desk, and more particularly, to a structure for varying a swing angle of an apparatus body with respect to a base.

2. Description of the Related Art

As a telephone apparatus normally used in an office, a home, or the like, there has been known an apparatus including a telephone body placed on a desktop and an angle variable apparatus that varies an installation angle of the telephone body.

For example, as disclosed in U.S. Pat. No. 7,104,516, a conventional angle variable apparatus having a tilt base, a tilt cover, and tilt arm. The tilt base is placed on a desk, and a cover bearing portion is formed at a front end portion of the tilt base. The cover bearing portion extends in a widthwise direction of the tilt base. A pair of engagement holes are formed at both ends of the cover bearing portion. The engagement hole includes a cylindrical hole portion and a fitting hole located above the cylindrical hole portion. The fitting hole has a slit shape having two opening edge portions parallel to each other.

A plurality of fixed concave portions are formed on an upper surface of the tilt base. The fixed concave portions are arranged with an interval in a depthwise direction of the tilt base.

The tilt cover is attached to a bottom surface of the telephone body. A cover swing shaft is formed at one end of the tilt cover. The cover swing shaft extends in a widthwise direction of the tilt cover. Cylindrical engagement portions are coaxially formed at both ends of the cover swing shaft. The engagement portion has two flat surfaces notched parallel to each other on an outer peripheral surface thereof.

The engagement portion of the cover swing shaft is inserted into the cylindrical hole portion through the fitting hole of the engagement hole. The cover swing shaft is swung in a shaft peripheral direction with the engagement portion inserted into the cylindrical hole portion, thereby tilting the flat surface of the engagement portion with respect to the opening edge portion of the fitting hole. Thus, the engagement portion of the cover swing shaft is retained and held to the cylindrical hole portion of the cover bearing portion, and the cover swing shaft of the tilt cover is swingably connected to the cover bearing portion of the tilt base.

The tilt arm is located between the tilt base and the tilt cover. One end of the tilt arm is swingably connected to the other end of the tilt cover. The connection portion of the tilt arm and the tilt cover employs the same configuration as the connection portion of the tilt base and the tilt cover. The other end of the tilt arm is hung in any one fixed concave portion of the tilt base. A tilt angle of the tilt cover with respect to the tilt base is varied by selecting the fixed concave portion in which the other end of the tilt arm is hung.

Therefore, it is possible to adjust the installation angle of the telephone body in a stepwise fashion according to operator\'s preference, thereby improving operability of the telephone body.

In the conventional angle variable apparatus for a telephone, an opening shape of the engagement hole of the tilt base and a shape of the engagement portion of the tilt cover have been studied so that the engagement portion of the tilt cover hardly comes off from the engagement portion of the tilt base.

However, for example, when the angle variable apparatus inadvertently falls down to receive a large impact, a relative positional relation between the tilt cover and the tilt base may be changed so that the flat surface of the engagement portion of the tilt cover is parallel to the opening edge portion of the fitting hole of the tilt base.

As a result, the engagement portion of the tilt cover comes off from the engagement hole of the tilt base and thus the function of the angle variable apparatus may be impaired.

Particularly, in the conventional variable apparatus, the shapes of the engagement portion of the tilt cover and the engagement hole of the tilt base are complex so that the tilt cover hardly comes off from the tilt base through normal use.

For this reason, once when the engagement portion of the tilt cover inadvertently comes off from the engagement hole of the tilt base, it takes a lot of time and effort for a person who does not know very much about the structure of the angle variable apparatus because the person has no idea how to attach the engagement portion into the engagement hole.

One of objects of the invention is to provide an angle variable mechanism capable of preventing a concave portion of a lock member from being detached from a guide groove, for example, even in case where the angle variable mechanism receives an impact.

According to one aspect of the invention, an angle variable mechanism includes: a fixed unit that has a pair of guide surfaces recessed in a circular arc shape and a pair of coaxial shaft portions located between the guide surfaces; a movable unit that includes an outer peripheral surface being curved in a circular arc shape and being in slidable contact with the pair of guide surfaces, a concave portion being opened in the outer peripheral surface and having a pair of side surfaces which face each other, a pair of guide grooves formed on the pair of side surfaces respectively and curved along the outer peripheral surfaces, to slidably receive the pair of shaft portions, and a pair of notches formed at respective edges between the pair of outer peripheral surfaces and the pair of side surfaces to guide the pair of shaft portions into the pair of guide grooves; and a lock member that is swingably supported with the fixed unit and interposed between the pair of side surfaces to regulate a swing angle of the movable unit with respect to the fixed unit, wherein the lock member has a pair of convex portions located on a swing center axis of the lock member, wherein the pair of convex portions are slidably fitted to the pair of guide grooves through the pair of notches respectively, wherein each of the convex portions has a first end portion and a second end portion separated from each other in a lengthwise direction of the guide grooves in a state where the pair of convex portions are received in the pair of guide grooves respectively, wherein a length of the convex portion between the first end portion and the second end portion is larger than an opening width of each of the notches in the lengthwise direction, wherein the second end portion is formed thinner than the first end portion, so that a gap is formed between the second end portion and an inner surface of the guide groove to allow the lock member to swing.